Wednesday, February 18, 2009

The Oleander Aphid

Oleander bushes need no special introduction as they are a familiar and splendid part of our gardens and landscapes, flowering as they do all summer long. However they do play another role which may not be as recognized and that is as as a source plant or "farmed" plant for beneficial insects.
In the warm and humorous Pedro Almodovar film Volver, the character of Sole says to her friend Augustina "Your Oleander looks wonderful" and so it does, flowering profusely in the enclosed courtyard of her Spanish home ."Yes, it didn't get aphids this year" comes the reply.
The aphid in question is the yellow bodied Oleander aphid Aphis nerii This has an important role on the other side of the world at Disneyworld where it is part of the Integrated Pest Management (IPM) program. The IPM department introduces to the oleander plants the tiny parasitic wasp Aphidus matricatriae which lays eggs on the aphid and cause the aphid's body to be covered with a hard shell like a "mummy" You often see these aphid "mummies " on rose bushes as well. Oleander leaves with aphid "mummies" are placed amongst vegetable crops and when the wasp matures, it emerges from the "mummy" to seek out aphids on the vegetables where they repeat the cycle.

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